The strikes of the conventional pneumatic nailer are achieved by a piston sliding inside the cylinder. An inner head housing is often placed on the top end of the cylinder. Under normal circumstances, the inner head housing is pushed tightly against the top end of the cylinder to keep the pressure from coming in. The inner head housing mentioned herein is the feature that the present invention aims to improve.
FIG. 1 shows the inner head housing of the conventional nailer. The inner head housing 10 is placed on the top end of the cylinder 11 of the nailer, and the space between the inner head housing 10 and the nail tip cover 12 is supported by a spring 13 so that it holds resilience. The side of the inner head housing 10 has an air-resistant ring 14, and a nail tip cover 12 extends downward to form a ring surface 15 for the air-resistant ring 14 of the inner head housing 10 to close tightly. When the nailer is not striking, as shown in FIG. 1, the pressure for the controlled air channel B1 and air inlet space B2 stayed on the same high pressure; therefore, the inner head housing 10 is pressed down by the spring 13 and pushed against the top end of the cylinder 11. At this time, the pressure inside the air inlet space B2 is kept out by the inner head housing 10 and is unable to enter into the cylinder 11 to push the piston 16. When the nailer is striking, as shown in FIG. 2, the high pressure of its controlled air channel B1 is leaked instantly and becomes low pressure. The pressure of the air inlet space B2 may push the inner head housing 10 upward, and press the spring 13 to accumulate restoring force. The top end of the cylinder 11 is interconnected with B2 space, and the pressure W of the air inlet space B2 may enter into the cylinder 11 to push the piston to achieve the striking moves. When the striking move is completed, the controlled air channel B1 may restore the high pressure to coordinate with the expansion of the spring 13 to restore the inner head housing 10 downward. Thus, the inner head housing 10 generates up and down movement each strikes.
However, the structure of the conventional inner head housing 10 still has the following issues. First, the nail tip cover 12 is made of metal material to meet the structural needs, and since the types of nail tip cover 12 vary, it is usually molded and shaped into details after two processes. The part of the ring surface 15 mentioned above must be very smooth, so that the air-resistant ring 14 can slide smoothly when the inner head housing 10 is moving up and down. However, the inner part of the nail tip cover 12, where the ring surface 15 mentioned above is placed, is deep; therefore, the challenge of processing its smooth surface increases significantly and the result fails to meet the demand of smoothness, which wears out the air-resistant ring 14 and shortens its shelf life.
Thus, to overcome the aforementioned problems of the prior art, it would be an advancement in the art to provide an improved structure that can significantly improve the efficacy.
To this end, the inventor has provided the present invention of practicability after deliberate design and evaluation based on years of experience in the production, development and design of related products.